1988891 has 2 divisors, whose sum is σ = 1988892. Its totient is φ = 1988890.

The previous prime is 1988887. The next prime is 1988897.

It is a happy number.

1988891 is nontrivially palindromic in base 10.

It is a weak prime.

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 1988891 - 2² = 1988887 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1988897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 994445 + 994446.

It is an arithmetic number, because the mean of its divisors is an integer number (994446).

2^1988891 is an apocalyptic number.

1988891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1988891 is an equidigital number, since it uses as much as digits as its factorization.

1988891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 44.

The square root of 1988891 is about 1410.2804685594. The cubic root of 1988891 is about 125.7583973618.

The spelling of 1988891 in words is "one million, nine hundred eighty-eight thousand, eight hundred ninety-one".